It's not hard but you will have to let most all the coolant out of the system. The biggest risk is getting air stuck in the system. That's minimized though if you don't have to remove the coolant plugs in the block which you don't.

Here is a pic of the housing, this one is for a motor with an OEM oil cooler but it's basically the same. The housing has an O-Ring gasket not a fiber one so you will be able to reuse it no problem. Make sure you take notice of which way the thermostat is facing. Be prepared for another flood of coolant when it comes out too.